TODO

#  $Id$

Stuff that needs to get done:

* Support "packet math" more cleanly.  packet = l2 + l3 + l4.  (yes, this
works, but is contrary to how pack is used

* Implement inter-layer knowledge, so that, for example, you can build a UDP
datagram and it will know that IPv4 is typically its parent and that the
checksum can automatically pull in the parent source and destination IP
addresses

* SCTP checksum

* Better error handling, argument raising and checking

* Better versioning system for gems

* Better generic support for dynamic/optional fields

* Update all examples so that they use the files relative to their directory if
the gem is not installed so that users do not have to install the gem to try
the examples